I need Populus deltoides clones.

I am looking to purchase improved high yielding Poplar clones,
especially clones resistant to rust (Melampsora medusae, M. larici
populina) and also resistant to Marssonina.
Can you help, either directly or by giving me the name, address,
telephone, fax or e-mail of someone who can.
Thankyou
Harold Churchill
South Africa